Duplex steam engine



(No Model.) 7 Sheets-Sheet I.

I M. w. HALL.

DUPLEX STEAM ENGINE. I No. 349,157. Patented Sept. 14, 1886.

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DUPLEX STEAM ENGINE.

Patented Sept. 14, 1886.

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7 SheetsSheet 3.

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M. W. HALL. DUPLEX STEAM ENGINE.

Patented Sept. 14, 1886.

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(No Model.) -7 SheetsSheet 4.

M. w. HALL.

I DUPLEX STEAM ENGINE. No. 349,157. Patented Sept. 14, 1886.

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(No Model.) 7 Sheets-Sheet 5.

M. W. HALL. DUPLEX STEAM ENGINE.

No. 349,157. Patented Sept. 14, 1886.

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(No Model.)

M. W. HALL. DUPLEX STEAM ENGINE.

Patented Sept. 14, 1886.

INVENTOR:

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M. W. HALL.

DUPLEX STEAM ENGINE. No. 349,157. Patented Sept. 14, 1886.

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By his Attorneys,

N. PEYERS. Pbfl'lu-Uihognpher, Wuhinginn, D. C.

- UNITED STATES PATENT FFICE.

MILAN \V. HALL, OF PLAINFIELD, NE? JERSEY, ASSIG-NOR TO THE HALL STEAMPUMP COMPANY, OF SAME PLACE.

DUPLEX STEAM-ENGINE.

SPEGIFICATION forming'part of Letters Patent No. 349,157, datedSeptember 14, 1886.

Application filed June 25, 1886. Serial No. 406,238. (No model.)Patented in France July 1, 1884, No. 163,084; in Germany July 2, 1884,No. 29,990; in England July 12, 1884, No. 10,097; in Belgium August13,1884,No. 66,018, and in Canada July 17, 1885, No. 22.049.

T0 aZZ whom it may concern.-

Be it known that I, MILAN WV. HALL, a citizen of the United States,residing in Plainfield, Union county, in the State of New J ersey, haveinvented certain new' and useful Improvements in Duplex Steam-Engines,of which the following is a specification.

This invention is the subject of patents in Great Britain, No. 10,097,dated July 12,1884; in Germany, No. 29,996, dated July 2, 1884;; inFrance, No. 163,084, dated July 1, 1884; in Belgium, N 0. 66,018, datedAugust 13, 1884, and in Canada, No. 22,049, dated July 17,1885.

This invention relates to duplex engines of that class wherein thevalves are actuated by steam-pressure alone, the two enginesreciprocally controlling each other. It is most particularly animprovement upon the engine disclosed in my United States Patent No.

801,363, dated July 1, 1884. The chief distinguishing feature of theduplex engine described in that patent consists in the arrangement ofsteam-passages leading from the cylinder of each engine across to thevalve-chest of the other engine, in order that steam from the cylinderofone engine shall cross overto the valve-chest of the other engine, andby direct impingement actuate the valve therein. Each valve controls thepassage of steam from the cylinder of its own engine to actuate thevalve of the other engine, and in like manner controls the passage ofthe exhaust-steam from the valve-chest of the other engine to the mainexhaust. In operating the engine constructed according to that patentsome trouble has .been at times experienced, owing to the liability ofthe valves to move prematurely, thereby causing the-pistons to makeshort strokes.

My present invention aims to overcome this defect; and to this end itinvolves two improvements onthe engine shown in my said patent: first,such an arrangement of the steam and exhaust passages to and from thevalvechests that the back-pressure in the cylinders will be conductedequally to opposite sides of the valve-pistons, and, consequently, beimpotent to move the valves prematurely; and, second, the loading of thesteam-actuated valves to such extent that no mere ineferring to thisfigure, A is the duplex steamengine, and B thepump. The twosteam-cylinders are arranged in line with the two pumpcylinders, as iscustomary in duplex pumpinggine constructed as a pumping-engine; Re-

engines, and are connected by a yoke, a. Each 55 engine has onepiston-rod, b, which bears the steam-piston on one end and the pumppiston or plunger on the other end. The pump B may be of any desiredconstruction, and forms no part of this invention.

Figs. 2 to 7, inclusive, illustrate the preferred construction of myimproved duplex engine. Fig. 2 is a vertical longitudinal mid-' sectionof one engine, as denoted by the line 2 2 in Fig. 3. Fig. 3 is atransverse section through the two engines, as denoted by the lines 3 3in Figs. 2, 4, and 6. Fig. 4 is a plan of the steam-cylinders alone, thevalve-chests having been removed. Figs. 5 and 6 show the port-plateremoved. Fig. 5 is a plan of the under side of this plate, and Fig. 6 isa plan of its upper side. Fig. 7 is a plan of the under side of thevalve-chests and their connecting-passage. Fig. Sis a diagramillustrating all the working parts and steampassages in one view andnearly in the same plane. Figs. 9 and 10 are similar diagramsillustrating modifications. Fig. 11 is a fragmentary longitudinalsection on lines 11 11 in Figs. 3 and at, showing a slight modification.0

Referring to Figs. 2 to 7, O O are the two steam-cylinders, and D D aretheir pistons fixed on the piston-rods b b. Each cylinder 0, as usual,which opens into the main exhaust-passage E. This passage extends acrossbetween the ports 0 e of the two engines and leads to an outlet, 13,Fig. 4, where the exhaust-pipe F, Fig. 1, is to be connected. Aport-plate, G, iits over the fiat top of the two cylinders G 0, Figs. 2and 3, and the several ports 0 c, d d, and c extend up through it. Overthis plate works a flat slide-valve, H, Fig. 2, which operates in theusual way. It is moved back and forth by a plunger, I, the enlarged endsof which form pistons, which work in cylindrical chambersf f in thesteamchest J. The valve H, plunger 1, and steamchest J of the otherengine are of the same construction. The two steanrehests J J areconnected by a steam-passage, K, Fig. 3, and they fit over the plate G,as shown. Through the ends of the plate G are formed two holes, 9 g,Figs. 5 and ti, which open into the steamspaces It 71, Fig. 3, in thesteam-chests J J, and coincide with two cavities, g 1 in thecylinder-casting beneath. One of these cavities is closed by a plug, Z,and the steam-pipe L connects with the other. Thus the steam-pipe may beconnected to either side of the engine, and the steam ilows from itthrough the cavity 5 and hole 9 into the interior of one steamchest, andthence through the passage K to the other steam-chest.

Referring to Fig. 2, where the valve H is standing at the right, thesteam flows from the steam-chest down the port 0 into the cylinder C,where it drives the piston I) toward the right, and the exhaust steamescapes through the port (1 under the valve A into the port 0 andexhaust-passage E. hen the piston moves far enough to the right, itcovers the exhaust-port d, and the remaining steam in front ofit acts asa cushion to stop the piston easily.

Referring to Figs. 2, 3, and 4, there are two small steam-ports, '1' andi, in each cylindereasting, which open into the cylinder, as shown.Holes or ports '1 '1" are also formed through the plate G, coincidingwith those in the cylinder-casting. These ports '1' i open upward underthe valve H or H, and each is arranged in line with two other ports, asshown in Fig. 6. The six ports are thus ar ranged in two rows of threeeach, all covered by the valve. In one row is the cylinder-port i, aconnection-port, j, and an exhaustport, 7;. In the other row is thecylinder-port '11. a connection-port,j, and an exhaust-port, 7.1. Thevalves H H, Fig. 7, have each (in addition to the usual mainexhaust-cavity, 0) two grooves, in and m,which coincide with the tworows of ports. The connection-portsjj,being in the middle, always communicate with these grooves m m, and when the valve is at the right theyare connected through the grooves with the ports I; and i, respectively,(the ports i and It being then covered by the valve and closed,) andwhen the valve is at theleft the portsjj are connected,respectively,\vith the ports i and 'k, (the ports I: and 2" being thenclosed.)

The exhaust-ports L and L pass down through the plate G, and extend intotheexhaust-ports d and (1, respectively. They are formed by grooves 0 0on the under side of the plate, Fig. 5, and holes 0 0, drilled in thecylinder-easting, Fig. 4. The connection-ports j and j of each enginecommunicate through passages a and a, 1'espectively,\vith the chambers fand f, respectively,in the steam-chestof the other engine. These fourpassages a u a n are formed by grooves 1) 1) in the upper and lowerfaces of the plate G, as shown in Figs. 5 and 6. XVhere the passages a across each other the respective grooves p p are on opposite sides of theplate, so that they do not interfere, and they connect through the plateby holes 1) p. \Vhere these grooves p 1) end at q q q q, Fig. 6, thepassages 11. a a a are continued upward by holes 1 r r r, Fig. 7, formedthrough the steam-chest J J into the chambers f f f, Fig. 2. All theseports and passages can be easily traced in the diagram, Fig. 8. Thesteam-pipe L is here shown in the center between the steam-chests. Thevalves ll H are shown in two parts, one being a section through theexlmust-cavity c and the other a section through the two grooves mm, which are supposed to bearranged end for end instead of side by side.Referring to this figure, the operation will now be described. Steamenters cylinder 0 through port 0 and drives piston D to the right. Vhenthe piston reaches nearly the end of its stroke it uncovers port 1'. andlive steam passes through that port, through groove in in valve H intoport j. thence through passage a to the chamber of the steam-chest J,thus pressing the plunger I to the left, as shown, and shifting thevalve H to the left. At the same time the steam in the chamber 1' at theother end of the plunger 1 escapes through passage 11, port j, groove inin valve H, and passage I: to the exhaust-passage d, where it joins theexhaust-steam flowing out from cylinder (J. The shifting of the valve Hadmits steam through the port 0 to cylinder (1/, and starts piston D(which has been at rest) on its leftward stroke. XVhen this pistonuncovers port '11, no effect is produced, because this port is coveredby the valve H; but when it uncovers port '11 steam will ilow throughthis port, through groove on or valve H into port j, and thence throughpassage a into chamber f of steam-chest .l, where it will shift plungerI and valve H to the left. Meanwhile the steam in chamberf at the leftof plunger 1 will escape through passagen to port th rough groovemofvalve H, and through port I.: into exhaust-port d of cylinder 0. Theshifting of the valve H to the left will start the piston l) (which willpreviously have come to rest) on its leftward stroke, and the sameseries of operations will be repeated. The passages a n enter thechambers/f at a little distance from the ends of these chambers, thusleaving a cushioning-space beyond them in the ends of the chambers tostop the plungers I I gently.

IIO

A groove, t, is formed in the wall of each chamber f f, and extends fromthe end of the chamber back a distance equal to the depth of thecushioning-space plus the width of the piston on the end of the plungerI or 1. When the plunger passes over and closes the opening it or a, thegroove t is opened to the pressure of steam in the middle of thesteamchest, and this stream flows through the groove. into thecushioning-space, thus stopping the movement of the plunger. Theplungeris then balanced with live steam at both ends. Assuming theplunger I to be at the right, as shown, as soon as the valve H moves tothe left, the chamber f is opened to the exhaust, and the superiorpressure of live steam in the chamberf will force the plunger I to theleft a short distance, as shown in dotted lines in Fig. 8, sufficient toclose the groove t and open the passage n. Then when the live steam fromcylinder 0 is admitted through the port '5 and passage n it will freelyenter the chamber f and force the plunger I to the left. In case at anytime the engine should fail to start when steam is turned on, it may bestarted by the hand-levers N N, Fig. 3, which are fixed to'rocking bars,which pass into the tops of the steam-chestsJJ and have arms P P,whichhang down into the slots in the plnngers I I. By rocking the hand-leversthe arms P P are caused to press against the ends of the slots and somove the plungers. Thesehand-levers form no essential part of themachine and may be omitted.

Prior to my present invention greatdifficulty has been experienced inallengines havingsteam-actuated valves, because of the tendency of theback-pressure in the cylinders when the valves are shifted toprematurely shift the valve pistons or plungers, and conse quentlyderange the action of the valves. This derangement results in.shortening the strokes of the engine-pistons, sometimes reducing them tosuch extent that the pistons execute merely a very short movement in themiddle of their cylinders.

The action of the back-pressure may be made clear by reference to Fig.8. The piston I) is here about to stop. Vhen it has remained stationaryuntil the piston D uncovers the port '13 in cylinder 0, the plunger Iand valve Hwill be shifted to the left. Previously the space in cylinder0 to the left of piston D has been filled with live steam at highpressme The shifting of the valve H connects this space with bothchambers f f of steamchest J, and this pressure of steam escapes fromcylinder 0 not only through the exhaustport d, but also through the port1' and passage to chamber f, and through the port cl, port k, andpassage n to chamber f. In my improved engine the same pressure passesfrom the cylinder 0 to both chambersff, so that the plunger 1 ispractically balanced; but in previous engines of this character theback-pressu re has been permitted to pass from the cylinder to onechamber, for f, and the other chamber has had direct communication withthe main exhaust, so that the pressures on opposite ends of the plungerI have been unequal, thus frequently shifting the plunger prematurely.This was the case to some extent with my former construction of engine,covered by my patent hereinabove referred to. In order that the changein that construction of engine which is necessary to apply my presentinvention may be readily understood, reference may be had to Fig. 10 ofthe accompanying drawings,which is a diagram very similar to the diagramFig. 9 in my said patent. In both diagrams the passages used exclusivelyfor exhaust-steam are tinted with horizontal lines. In my former patentthe exhaust-passages from the valve-chests, after passing the grooves inthe valve-stems, enter directly into the main exhaust. For instance,referring to Fig. 9 in my said patent, iston B has just uncovered theport i, and the valve D is being shifted toward the left. In so doingits grooves h h connect the passagei with the passagej, leading acrossto chamber L.- An instant previously the cylinder A to the left ofpiston B was filled with live steam at full pressure. The movement ofthe valve D un covers the exhaust b at the left and the steaminlet a atthe right, both at the same instant. The pressure in cylinder A (knownas the back-pressure) then escapes through exhaust b, and also throughpassages i and j to chamber L, and presses upon valve-piston g, tendingto force it to the left. From the main exhaust passage it leads intopassages P, thence .through groove h and passages i and k to chamber L,pressing against the piston g and tending to force it-to the right; butthe pressure thus exerted against the piston g is inferior to thatagainst its opposite side, and consequently the piston is apt to bemoved prematurely. This will occur whenever the preponderance ofbackpressure from the cyl inder A. is sufficient to overcome thefriction and inertia of the valve. That the two pressures are unequalmay be clearly seen by tracing the respective paths which must betraversed by steam from both sides of the piston 9 before it can escapeat the exhaust. Steam from the left side has only to pass throughpassages It, Z, and p in order to reach the exhaust, while steam fromits right side has to pass through passages j, j, and '5, cylinder A,exhaust-port b, and exhaust-passage d in order to reach the point wherethe passage 1) joins the main exhaust, which is afar more circuitouspassage. Furthermore, the backpressure in cylinder A falls rapidly asthe steam passes out to the exhaust, the pressure being at all timesgreatest in the cylinder and decreasing along the exhaust-passages;hence, while the right side of piston g is in direct communication withthe high pressure in cylinder A, and the left side is in equally directcommunication with the comparatively low pressure in theexhaust-passage, it is obvious that during the escape of the back-press-IIO ure from the cylinder there must be a much higher pressure againstone side of piston 1/ than against the other.

Referring now to Fig. 11) of the accompanying drawings, the essentialchange introduced by my present invention will be readily understood.The exhaust-passages It 7. I; 1. instead ofjoiniug the main exhaust I asbefore, outside of themain valve. extend to the cylinders U (1,respectively, or, what is substantially equivalent, to the exhaust-portsd d d (1'. Consequently the back-pressure from the cylinders has equallydirect access to both sides of the pistons I l, and the lat ter arebalanced by an equal pressure on opposite sides, and are no longerliableto be moved prematurely.

In my former construction the exhaust from the valve-piston chamberpassed directly to the main exhaust outside of the main valve, where theback-pressure is much less than in the cylinder, or in the exhaust-portinside of the main valve. In my improved construction the exhaust fromthe valve-piston chamber passes either into the opposite cylinder orinto the exhaust-port therefrom, and thence out through that port andthrough the main valve, being thus controlled and retarded by the mainvalve to the same extent as is the exhaust from the cylinder.

The construction shown in Fig. 10 is not preferred by me, for the reasonthat the valves H H, being balanced, are too easily moved in eitherdirection, so that a very slightinequality of pressure will shift them.On this account I now use slide-valvcs, as already fully described,which are loaded by the pressure of steam holding them down to theirseats. Suflicient friction is thus generated to resist anyslightpressure; but when the full pressure of steam comes against thevalve piston or plunger the valve is immediately shifted. Thisconstruction admits of some inequality of back-pressure on oppositesides of the valve-pistons without causing the premature shifting of thevalves. Henceit is not neces sary that the exhaust-passages from thevalvepiston chambers shall actually enter the cylinders U C, andinstead, for the sake of convenienee and cheapness of construction, Icause the passages 7.1 7: to enter the exhaust ports d (I at thepositionclearly shown in Fig. 8, or thereabout. In this case the ports (I 1]form continnations of the passageslc/H, leading to the cylinders.

Fig. 11 shows a slight modification, wherein the exhaust-passages L 7;actually enter the main cylinders. The section is chiefly through oneexhaust-passage, 7s, and one steam-passage, t.

Another feature of my inventionI will now describe. \Vhcrc the ports 1't" enter the cylinders, their open ends are designated by black dots.Formerly I provided only these openings, which were covered anduncovered by the piston in its movement. During the time that the pistonis passing over one of these ports the port is covered up and allcommunication with the cylinder is cut off for an instant. I iinditdesirable that lheseports shall always be in eommunieaiion with thecylinder on one side or the other ofthe piston. in order to accomplishthis to the same effect as though the piston were only as thick as thewidth of these ports, I form grooves m in the inner wall of thecylinder, extending from the open ends of the ports '1? 2",respectively. toward the ends of the cylinder for a length equal to thewidth of the piston, or rather for a distance equal to the width of thepackingrings, (the width of the openings 1' or 1 being considered partof the length of the grooves.) as clearly shown in Figs. .5 and S.

Fig. 9 is a diagram similar to liig. 8,which shows amodiiiedconstruction oi the engine. The general operation is the same; but thepassages a a are used only for comlueting the live steam to shift theplungers or pistons .l I. The exhaust-steam from the chambers ff isconducted away by additional 'iassages It It. which are tinted in thefigure. The cushioninggroovcs I tare omitted, the plungers l I beingcushioned in the same way as the pistons I) l).

The plate G constitutes an important feat ure of my present invention,as it greatly improves and cheapcns the construction of the engine andrenders all the stcampassages readily accessible in case of necessity.It is not essential that the steam-passages crossing over from eachcylinder to the opposite valvechest shall be formed by grooves in theplate Er, but only that they shall be fornucd by grooves along the jointbetween this plate and the valve-chests above and cylinders below. Thegrooves might be formed entirely in the jointing faces of thevalve-chcsts and cylinders, or half in those parts and hall'in theplate.

\Vhat I claim as my invention, and desire to secure by Letters Patent,is-

1. A. duplex stcanvcngine wherein the two engines reciprocally controleach other by means of steam-actuated valves constructed withsteamqmssages and exhaustqmssages e.\'- tending from opposite sides ofthe valve-operating piston or plunger of each engine, and communicatingwith the cylinder ofthe other engine in such manner, as described, thatthe baclepressure in the cylinder shall be conducted cqually. or nearlyso, to opposite sides of the valvcopcrating piston or plunger, andconsequently will be substantially balanced and impotent to move thepiston or plunger prematurely, substantially as set forth.

2. In a direct-acting duplex steam-engine having its valves operated bydirect steampressure, exhaust-passages leading from the opposite ends ofthe valve piston or plunger chambersinto the end portions of the maincylinders, as described,eaeh passage-way controlled by a valve, combinedand arranged as described, as and for the purposes set forth.

3. In a direct-acting duplex steam-engine scribed, as and for thepurposes set forth.

4. A duplex steam-engine wherein the two engines reciprocally controleach other by steam-actuated valves constructed with steampassages andexhaust-passages leading from opposite sides of the valve-operatingpiston or plunger of each engine, and communicating with the cylinder ofthe other engine in such manner, as described, that the back-pressurefrom the cylinder shall be conducted equally, or nearly so, to theopposite sides of the valve piston or plunger, and the valves operatedby said pistons or 'plungers constructed to be loaded. by a pressure ofsteam forcing them against their seats, whereby sufficient friction isgenerated to resist the accidental shifting of the valves by anyinequality of back-pressure transmitted through said passages, wherebysaid valves can be shifted only by the direct steam-pressure againsttheir operating pistons or plungers, substantially as set forth.

5. The improved construction of duplex engines having steam -actuatedvalves, which consists of the combination of the main cylinders, thevalve-chests, and an intervening plate, G, with the several steam andexhaust ports crossing between each engine and the valve-chest of theother, formed by means of grooves in the joints between said plate andthe cylinders below and valve-chests above, substantially as set forth.

6. The improved construction of duplex engines having steam-actuatedvalves, which consists in the combination, with the main cylinders andvalve-chests, of a port-plate, G, having grooves in its upper and lowerfaces, forming the passages crossing between each engine and thevalve-chest of the other, substantially as set forth.

7. In a duplex engine, thecombination of the two main cylinders, thevalve-chests, the port-plate G between said cylinders and valvechests,having grooves forming the passages crossing between the cylinder ofeach engine and the valve-chest of the other, and ports formed throughit, and the steam-actuated slide-valves in said valve-chests, arrangedto slide over said plate and to open and close the said ports therein,substantially as set forth.

8. In a duplex engine having steam-aetuated valves, the combination,with the valves and their actuating pistons or plunger-s, of thevalve-chests constructed with chambers fj" for said plungers, with portsa a entering the same near their ends, leaving a cushioningspace in theend of each chamber beyond the port a, and the cushioning-grooves M inthe said chambers,substantially as set forth,whereby when the plungernears the end of its stroke and cuts off the exhaust through a it openstand admits live steam in front of it to cushion against.

9. In a duplex engine having steam-actuated valves, the combination,with the main cylinders and pistons, of ports 2 1), leading from thecylinder of each engine through the valve thereof to the valve-chest ofthe other engine, and grooves m 00, formed in the cylinders, extendingfromsaid ports toward the ends of the cylinders a distance equal to theeffective length of the pistons, substantially as and for the purposeset forth.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

MILAN XV. HALL.

Vitnesses:

ARTHUR C. FRASER, GEORGE H. FRASER.

